An electric power steering apparatus is provided in which stably performing drive of FETs of an inverter can be achieved by means of a simplified constitution. The electric power steering apparatus drive-controls a motor through an inverter comprised of an FET bridge based on each-phase duty command values of pulse-width modulation (PWM) and perform assist control of a steering system. The electric power steering apparatus comprises a charge pump circuit and a bootstrap circuit that generate a booster power voltage for driving upper-FETs of the FET bridge, wherein the circuit having a higher voltage is used as the booster power voltage.
Legal claims defining the scope of protection, as filed with the USPTO.
1. An electric power steering apparatus that calculates each-phase duty command values of PWM, based on said each-phase duty command values, drives upper-FETs of an FET bridge through an upper-FET gate driving section and drives lower-FETs of said FET bridge through a lower-FET gate driving section, and performs an assist control of a steering system by drive-controlling a motor with an inverter comprised of said FET bridge, comprising: a charge pump circuit and a bootstrap circuit that are connected to said upper-FET gate driving section and are connected with each other through diodes, a voltage from one having a high voltage of said charge pump circuit and said bootstrap circuit is used as a booster power voltage to drive said upper-FETs, in response to a failure of said charge pump circuit is determined, said upper-FETs of said FET bridge is driven by using a voltage generated at said bootstrap circuit and said assist control is continued, and wherein said upper-FET gate driving section is configured to control said upper-FETs and said lower-FET gate driving section is configured to control said lower-FETs.
2. An electric power steering apparatus according to claim 1 , wherein determination of said failure of said charge pump circuit is performed based on a system voltage and an output voltage of said charge pump circuit.
3. An electric power steering apparatus according to claim 2 , wherein when said failure of said charge pump circuit is determined, each-phase duty command values of said upper-FETs are limited.
4. An electric power steering apparatus according to claim 1 , wherein said charge pump circuit is connected to a first diode and said bootstrap circuit is connected to a second diode, and said first diode and said second diode are connected with each other and are further connected to said upper-FET gate driving section.
5. An electric power steering apparatus according to claim 4 , wherein said first diode and said second diode are connected with each other in a reverse direction.
Cooperative Patent Classification codes for this invention. Click any code to explore related patents in that topic.
November 6, 2012
August 2, 2016
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